<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      //   var i = 20;
      //   console.log(++i);
      //   var j = 30;
      //   console.log(j++);
      //   console.log(j);
      var a = 10,
        b = 20;
      console.log(a++ + ++b + ++a + b++);
      //   10     21   12   +  21
      console.log(a++ + ++b);
    </script>
  </body>
</html>
